std::vector::data
From cppreference.com
                    
                                        
                    
                    
                                                            
                    
| T* data(); | ||
| const T* data() const; | ||
Returns pointer to the underlying array serving as element storage. The pointer is such that range [data(); data() + size()) is always a valid range, even if the container is empty.
| Contents | 
[edit] Parameters
(none)
[edit] Return value
Pointer to the underlying element storage. For non-empty containers, returns &front()
[edit] Complexity
Constant.
[edit] Exceptions
| (none) | (until C++11) | 
| 
noexcept specification:   noexcept | (since C++11) | 
[edit] See also
| access the first element (public member function) | |
| access the last element (public member function) | |